1. Field of the Invention
The present invention relates to a jet propulsion boat of the type in which the hull is advanced by discharging a jet water stream through a nozzle and the hull is turned around to the left or to the right by changing the direction of the nozzle by a steering handle.
2. Description of Background Art
The jet propulsion boat obtains its propulsion force by discharging a jet water stream and changes the direction of the hull by changing the direction of the jet water stream. Therefore, it cannot turn around without the jet water stream.
As a general action of a human, for example, when evading an obstacle, he/she tends to reduce the speed of the boat and operate the steering handle to the left or the right. Reducing the vessel speed means to close the throttle. Even when turning the steering handle to the left or the right with the throttle closed, it cannot obtain a sufficient jet water stream because the number of revolution of the engine is low. Consequently, he/she cannot turn the hull around at will. This is especially obvious when the speed of the hull is high.
As a technology for compensating such characteristics of jet propulsion boats, U.S. Pat. No. 6,159,059, for example, is known.
The aforementioned technology is, according to FIG. 2 and FIG. 3 in the publication of the same patent, constructed in such a manner that one end of the throttle cable 44 is connected to the throttle regulator 46 and the other end of the throttle cable 44 is connected to the throttle lever 34. A throttle return spring 49 is disposed for restoring the throttle lever 34. A compressive material 52 is disposed at the foot of the throttle lever 34, so that the throttle regulator 46 is prevented from closing suddenly when the throttle lever 34 is released. A prescribed jet water stream is maintained for a certain period of time even after the throttle lever 34 is returned.
However, after “a certain period of time” for maintaining a prescribed jet water stream has passed, the quantity of water is reduced and thus the turnability is lowered. This lowers usability. In addition, when the speed of the hull is low, it is not necessary to maintain a jet water stream.